Someone threatened to detonate a bomb at a Kmart in South Jersey on Tuesday if funds weren't added to a prepaid money card.Getty Images

MIDDLE — No explosives were found in a Cape May County Kmart after a person phoned in a bomb threat to the store on Tuesday, authorities said.

The caller claimed that an explosive device would be detonated in the store if funds weren't added to a prepaid Green Dot MoneyPak card, the Cape May County Prosecutor's Office said.

K-9 units swept the store in the Rio Grande section of Middle Township following the 5:15 p.m. threat and found nothing dangerous, authorities said.

The call is apparently part of a growing scam involving the prepaid cards, according to the prosecutor's office. The person who phoned in the threat would have had to receive a 14-digit security code to be able to transfer money to another account.

In another variation of the attempted fraud, authorities said the scammer phones would-be victims and tells them they've won a sweepstakes but will need to pay fees to collect the prize. The person is instructed to purchase a Green Dot MoneyPak card and reveal the security code to the winner.

Authorities warned those who use the prepaid cards not to provide the security code to anyone and not to use them to pay any fees after winning a prize. The information on the cards should also not be shared by email or phone, the Cape May Prosecutor's Office said.